3D MERGE与3D SPACE STIR序列在腰椎间盘突出症检查中的应用比较

目的:对比三维多回波恢复梯度回波(3D MERGE)、三维可变反转角快速自旋回波(3D SPACE STIR)序列在腰椎间盘突出症(LDH)检查中的应用效果。方法:选择2020年1月~2022年11月收治的135例LDH患者,回顾性分析患者临床和磁共振成像(MRI)资料,所有患者均接受常规MRI扫描及3D MERGE、3D SPACE STIR序列扫描,对比3D MERGE、3D SPACE STIR序列测量神经根直径的一致性,评价两种序列的图像质量参数[信噪比(SNR)、对比噪声比(CNR)]、图像清晰度评分。结果:3D MERGE和3D SPACE STIR序列测量的L3~S1神经根直径比较差异无统计学意义(P>0.05),且两组序列测量的L3、L4、L5和S1直径均显示出较高相关性(r=0.957,0.986,0.975,0.972,P<0.05);3D MERGE序列的SNR及CNR均高于3D SPACE STIR序列,神经根显示分级、图像清晰度评分优于3D SPACE STIR序列,差异有统计学意义(P<0.05)。结论:3D MERGE、3D SPACE STIR序列在LDH神经根直径测量中具有极高一致性,3D MERGE序列较3D SPACE STIR序列能够更清晰显示神经跟的解剖形态,图像质量更好。

高分辨率血管壁成像时3D SPACE T1压脂与非压脂序列对MCA狭窄病人图像信号、血管壁及斑块的影响

目的:探究高分辨率血管壁成像时利用可变翻转角实现最优化采集的3D快速自旋回波序列(3D-SPACE)T1压脂与非压脂序列对大脑中动脉(middle cerebral artery,MCA)狭窄病人图像信号、血管壁及斑块情况的影响。方法:选取2021年1月—2022年12月于滨州市中心医院接受颅内磁共振血管成像(MR angiography,MRA)检查并确诊的MCA狭窄患者72例为研究对象,患者均接受MCA MRI检查,然后再分别用3D SPACE T1压脂与非压脂序列测量,分析图像信号差异情况,对比不同序列测量的血管断面、管腔及斑块面积情况及图像质量主观评价;分析不同医师图像质量评分的一致性情况。结果:72例患者中,不同序列测量均可以清晰地将MCA斑块显示出来,但测量出的信号存在明显的差异。不同序列测量血管断面、管腔面积对比差异不显著(P>0.05);3D SPACE T1非压脂序列测量斑块面积大于压脂序列测量面积(P<0.05);2种序列管腔显示情况对比差异无统计学意义(P>0.05),其他图像质量对比差异有统计学意义(P<0.05)。2名医生图像质量评分具有良好的一致性。结论:高分辨率血管壁成像时3D SPACE T1非压脂序更有助于对MCA狭窄病人图像信号、血管壁及斑块的测量,可为临床提供治疗依据。

腰骶丛神经根成像中T23D SPACE序列的技术优化研究

目的:探讨T23D SPACE序列在腰骶丛神经根中的应用及其参数优化。方法:前瞻性招募并收集46名正常志愿者的临床与影像资料,所有志愿者均行常规T23D SPACE(方法A)、优化后T23D SPACE(方法B)磁共振扫描,并比较2种方法的扫描时间,第4~5腰神经、第1~4骶神经、坐骨神经的神经显示情况,第5腰神经根节中、节前、节后的信噪比(SNR)、对比度噪声比(CNR)_(神经-肌肉)、对比度(CR)_(神经-肌肉值)。优化后T23D SPACE序列(方法B)主要优化了TR、TE、加速因子(回波链)、脂肪抑制方式、血液抑制方式、层厚等参数。结果:(1)方法A扫描时间为356 s,方法B扫描时间为229 s。(2)在神经显示评分比较中,第4、5腰神经,第1~4骶神经和坐骨神经的显示评分在2种方法之间差异无统计学意义。(3)第5腰神经根的节中SNR值(286.842±75.822 vs 376.784±111.880)、CNR_(神经-肌肉值)(389.199±106.824 vs 522.683±159.883)、CR_(神经-肌肉值)(0.798±0.037 vs 0.830±0.038)在2种方法间比较,差异均有统计学意义(P<0.05)。(4)第5腰神经根的节前SNR值(198.758±52.966 vs 260.378±79.631)、CNR_(神经-肌肉值)(254.720±74.904 vs344.948±112.041)、CR_(神经-肌肉值)(0.718±0.070 vs 0.762±0.056)在2种方法间比较,差异均有统计学意义(P<0.05)。(5)第5腰神经根的节后SNR值(161.400±46.883 vs 206.849±59.706)、CNR_(神经-肌肉值)(197.684±63.776 vs 263.240±80.910)、CR_(神经-肌肉值)(0.663±0.068 vs 0.711±0.058)在2种方法间比较,差异均有统计学意义(P<0.05)。结论:常规T23D SPACE序列与优化后的序列均可以显示腰骶神经,优化后扫描更快,神经显示中第5腰神经根的信噪比、对比度均比常规T23D SPACE序列高。

3D MEDIC和3D SPACE磁共振神经成像在腰骶丛神经根的一致性对比研究

目的验证三维多回波数据联合成像(three dimensional multi-echo data imagine combination with selective water excitation,3D MEDIC WE)和三维快速自旋回波成像(three dimensional sampling perfection with application optimized contrasts by using different flip angle evolution,3D SPACE STIR)序列在腰骶丛神经根成像中的可行性和重复性。方法将55例受试者分为腰椎无异常表现的正常对照组(20例)、单纯性腰椎间盘突出症(lumbar disc herniation,LDH)组(20例)和慢性炎性脱髓鞘性多发性神经根神经病症(chronic inflammatory demyelinating polyradiculoneuropathy,CIDP)组(15例),分别应用两种腰骶丛神经根成像,评价图像质量参数信噪比(signal to noise ratio,SNR)、对比噪声比(contrast to noise ratio,CNR)和对比度(contrast ratio,CR),并验证正常对照组、CIDP组和LDH组测量神经根直径的一致性。结果两序列测得神经根直径的一致性较高(正常组r=0.95,CIDP组r=0.99,LDH组r=0.97,P<0.001),图像质量评价指标显示,3D SPACE STIR序列在SNR、CNR和CR三项指标中占优,3D MEDIC WE定性评估图像质量评分较高。两序列均能清晰显示正常腰骶丛神经根、病变所致的弥漫性形态增粗神经根以及间盘突出受挤压变形的神经根。结论3D MEDIC WE和3D SPACE STIR序列可应用于腰骶丛神经根成像,两序列对正常和异常形态、走行的神经根评估具备很高的可行性和重复性。综合考量临床图像的定性、定量评价,可择优选择恰当的序列为腰骶丛神经根成像提供影像支持。

PartLabeling:A label management framework in 3D space

Background In this work,we focus on the label layout problem:specifying the positions of overlaid virtual annotations in Virtual/Augmented Reality scenarios.Methods Designing a layout of labels that does not violate domain-specific design requirements,while at the same time satisfying aesthetic and functional principles of good design,can be a daunting task even for skilled visual designers.Presenting the annotations in 3D object space instead of projection space,allows for the preservation of spatial and depth cues.This results in stable layouts in dynamic environments,since the annotations are anchored in 3D space.Results In this paper we make two major contributions.First,we propose a technique for managing the layout and rendering of annotations in Virtual/Augmented Reality scenarios by manipulating the annotations directly in 3D space.For this,we make use of Artificial Potential Fields and use 3D geometric constraints to adapt them in 3D space.Second,we introduce PartLabeling:an open source platform in the form of a web application that acts as a much-needed generic framework allowing to easily add labeling algorithms and 3D models.This serves as a catalyst for researchers in this field to make their algorithms and implementations publicly available,as well as ensure research reproducibility.The PartLabeling framework relies on a dataset that we generate as a subset of the original PartNet dataset consisting of models suitable for the label management task.The dataset consists of 10003D models with part annotations.

2D TSE与3D SPACE序列对直肠癌术前T分期的诊断价值比较

目的比较三维可变翻转角各向同性快速自旋回波(3D SPACE)序列与传统二维快速自旋回波(2D TSE)序列对直肠癌术前T分期的诊断价值。资料与方法选取2018年1月—2019年12月青岛大学附属医院收治的直肠癌患者75例,术前进行2D TSE及3D SPACE序列扫描,计算2D TSE及3D SPACE序列图像的信噪比(SNR)、对比噪声及图像评分评估图像质量。以术后病理结果为“金标准”,比较2D TSE及3D SPACE序列诊断直肠癌术前T分期的准确度。结果2D TSE和3D SPACE序列的图像质量在显示直肠浆膜层或外膜[3.00(2.00,3.00)比3.00(3.00,3.00);Z=−0.16,P=0.990]、肠周脂肪[3.00(3.00,3.00)比3.00(3.00,3.00);Z=−0.259,P=0.800]、直肠系膜筋膜[3.00(3.00,3.00)比3.00(3.00,3.00);Z=−1.27,P=0.210]、瘤体[3.00(3.00,3.00)比3.00(3.00,3.00);Z=−0.03,P=0.990]比较,差异无统计学意义。3D SPACE序列在显示直肠黏膜层[3.00(2.00,3.00)比3.00(3.00,3.00);Z=−2.47,P=0.013]、直肠肌层[3.00(2.00,3.00)比3.00(3.00,3.00);Z=−3.21,P=0.001]方面图像质量更高。对于瘤体,3D SPACE序列的SNR优于2D TSE序列(119.95±39.83比83.94±40.34;t=−2.54,P=0.016);对于脂肪(213.56±95.26比191.22±59.47;t=0.80,P=0.430)及肌肉(41.86±19.34比40.40±15.58;t=0.24,P=0.820),2D TSE及3D SPACE序列的SNR差异无统计学意义;两序列对比噪声比差异无统计学意义(19.36±10.11比27.54±18.72;t=−1.54,P=0.140)。与术后病理结果对比,2D TSE序列的诊断一致性(Kappa=0.49,P=0.00)比3D SPACE序列低(Kappa=0.95,P=0.000),两序列对T分期的诊断准确度分别为76.00%和98.67%。结论2D TSE和3D SPACE序列显示直肠浆膜层或外膜、肠周脂肪、直肠系膜筋膜及瘤体一样可靠。3D SPACE序列对于显示直肠黏膜层及直肠肌层较2D TSE序列更优越。对于直肠癌的术前T分期,3D SPACE序列较传统高分辨2D TSE序列的诊断准确度更高,可更好地为临床制订治疗方案提供影像学依据。

3.0T MRI 3D Space序列对颅脑动脉斑块出血的诊断应用

目的探讨磁共振可变翻转角的三维快速自旋回波(3D-sampling perfection with application optimized contrast using different flip angle evolutions,3D-SPACE)序列检测大脑中动脉斑块内出血(intraplaque hemorrhage,IPH)的成像情况及其诊断价值。方法选取我院就诊的脑动脉粥样硬化的患者100例,所有患者均接受常规MRI检查、3D序列亮血时飞法MR血管成像(time-of-flight magnetic resonance angiography,TOFMRA),同时接受3D-SPACE序列检查。根据常规序列(T1WI、T2WI、3D TOF、T1WI-CE)图像综合评估IPH,并根据患者的临床、影像学结果对所有患者进行评估,将患者分为有症状组和无症状组。对比两组患者3D-SPACE序列评估斑块信号的高低情况,同时对比3D-SPACE及常规MRI各序列对IPH的评估效果。结果有症状组72例患者中通过3D-SPACE序列共检测出142个斑块,其中斑块病灶信号强化2级98个(69.1%),仅11个(7.7%)斑块无信号强化;无症状组28例患者中共检测出49个斑块,其中35个斑块(71.5%)表现为无强化或1级强化。有症状组患者中IPH的发生率显著高于无症状组,同时有症状组患者中3D-SPACE序列信号强化程度显著高于无症状组,差异具有统计学意义(P<0.05)。评估191个斑块中共有112个为IPH,结果提示TOF、T1WI、3D-SPACE序列评估IPH具有较高的敏感性、特异性和一致性,其中3D-SPACE显示IPH的一致性最高。结论3.0T MRI 3D-Space序列能够有效的提示MCA粥样斑块的IPH情况,为合并颅内血管脑动脉斑块患者的危险程度评估及治疗提供参考依据,具有较高的诊断和临床价值。

术前增强3D SPACE STIR序列在减少L_(4~5)极外侧椎间融合术后股神经损伤中的研究

目的探讨术前增强3D SPACE STIR序列检查在减少L_(4~5)极外侧椎间融合术(extreme lateral interbody fusion,XLIF)术后股神经损伤中的作用。方法回顾分析2017年9月至2019年2月采用XLIF治疗37例L_(4~5)节段退行性疾病患者。传统组17例,男9例,女8例;年龄41~82岁,平均(63.3±12.7)岁;术前行传统MRI检查确认责任节段,术中采用椎间隙中点(Ⅱ~Ⅲ区交界处)处进行穿刺入路。改良组20例,男13例,女7例;年龄48~85岁,平均(65.4±12.3)岁;术前先行增强3D SPACE STIR序列检查,个体化选择穿刺点进行穿刺入路。统计改良组穿刺点分布情况,两组术后即刻、3个月、6个月、1年股神经损伤例数,术前及术后3个月、6个月、1年疼痛视觉模拟评分(visual analogue scale,VAS)及Oswestry功能障碍指数(oswestry disability index,ODI)。结果传统组17例患者选择Ⅱ~Ⅲ区交界处作为穿刺点;改良组20例患者中,穿刺位置选择Ⅰ区内1例,Ⅰ~Ⅱ区交界处13例,Ⅱ~Ⅲ区交界处6例。所有患者术后均获得随访,随访时间1年。随着时间推移,术后VAS及ODI均较术前明显改善,两组患者都未出现融合器下沉、移位、血管损伤、输尿管损伤的并发症。改良组术后即刻股前区麻木、下肢运动障碍例数均小于传统组(P<0.05)。结论根据增强3D SPACE STIR序列检查制定个体化XLIF可减少XLIF术后股神经损伤。

3D printing in space:from mechanical structures to living tissues

3D printing stands at the forefront of transforming space exploration,offering unprecedented on-demand and rapid manufacturing capabilities.It adeptly addresses challenges such as mass reduction,intricate component fabrication,and resource constraints.Despite the obstacles posed by microgravity and extreme environments,continual advancements underscore the pivotal role of 3D printing in aerospace science.Beyond its primary function of producing space structures,3D printing contributes significantly to progress in electronics,biomedicine,and resource optimization.This perspective delves into the technological advantages,environmental challenges,development status,and opportunities of 3D printing in space.Envisioning its crucial impact,we anticipate that 3D printing will unlock innovative solutions,reshape manufacturing practices,and foster self-sufficiency in future space endeavors.

Relations between Directional Derivatives for Smooth Functions in 2D and 3D Spaces

In this paper, relations between directional derivatives are considered for smooth functions both in 2D and 3D spaces. These relations are established in the form of linear combinations of directional derivatives with their coefficients having simple form and structural regularity. By them, expressions based on directional derivatives for some typical differential operators are derived. This builds up a solid mathematical foundation for further study on numerical computation by the finite point method based on directional difference.

1.5T磁共振3D-SPACE序列与3D-TSERT序列在MRCP成像中的应用对比

目的:通过MR可变翻转角的三维快速自旋回波(3D sampling perfertion with application optimized contrasts using deifferent flip angle evolutions,3D-SPACE)序列与三维快速恢复快速自旋回波(3D-TSE Retore,3D-TSERT)序列对胰胆管水成像(MR cholangiopancreatgrapgy,MRCP)中的成像质量进行对比,优化MRCP的成像序列。方法:对48位受检者分别用3D-SPACE序列与3D-TSERT序列行MRCP检查,将采集到的影像利用siemens 3D软件进行MIP(maxium intensity projection)重建,并对2种图像的显示情况进行分析比较。结果:3D-SPACE序列的MRCP显示肝段胆管、胰管的效果明显优于3D-TSERT-MRCP序列(P﹤0.05),2种成像序列显示左右肝管、肝总管、胆囊、胆总管的效果差异无显著性意义(P>0.05)。结论:在1.5TMRI检查中,应用3D-SPACE序列的MRCP在检查时间及成像质量上都优于3D-TSE序列,应成为常规MRCP的首选序列。

对比增强3D STIR SPACE序列对子宫内膜异位症患者骶丛神经异常的显示

【目的】探讨增强3D STIR SPACE序列对盆腔子宫内膜异位症患者骶丛神经异常的显示价值,并与增强3D VIBE序列进行对比。【方法】病例组包括30名子宫内膜异位症患者,对照组包括20名健康女性,均接受盆腔MRI检查,包括对比增强3D STIR SPACE序列和增强3D VIBE序列。评估骶丛神经显示的图像质量以及子宫内膜异位症患者中的骶丛神经侵犯。【结果】对照组和病例组中,3D STIR SPACE序列和3D VIBE序列均能很好地显示骶丛神经纤维(P<0.001)。阅片者应用3D-STIR-SPACE序列对病变的诊断信心分数一致性较强(Kappa=0.684,P<0.001),应用3D-VIBE序列的诊断信心分数一致性一般(Kappa=0.130,P=0.386)。【结论】对比增强T2-SPACE序列和3D VIBE序列能够清晰显示骶丛神经,前者对盆腔子宫内膜异位症患者骶丛神经异常的显示更有优势。

基于dSPACE的汽车电动玻璃升降器防夹控制的半实物仿真与验证

提出了针对电动玻璃升降器双霍尔传感器与直流电机电流检测(DHSCD)防夹控制算法的"V字形"开发流程;利用Simulink建立系统模型对防夹控制算法与电动玻璃升降器的功能性和可靠性进行离线仿真验证;在通用快速控制原型仿真方法的基础上,针对DHSCD防夹控制算法设计了特有的仿真方案;完成了目标控制器的自动代码生成;提出了适用于电动玻璃升降器DHSCD防夹控制算法的硬件在环仿真验证平台。离线仿真和半实物实时仿真结果表明,基于d SPACE开发的电动玻璃升降器防夹控制算法具有良好的可靠性与环境适应性。

基于dSPACE的AMT电控操纵系统试验台设计

以AMT为研究对象,以实现电控操纵选换挡为目标,设计电控操纵系统试验台。由d SPACE控制变速器试验台操纵机构自动完成选换挡动作,通过运动模拟软件计算和试验验证两种方法获得换挡操纵杆运动过程中操纵杆特定点位的空间位置、速度和定向载荷及其变化率等系列参数。对比验证表明该设计方案合理可行,对开发AMT操纵系统测试装置具有借鉴意义。

基于dSPACE的嵌入式车辆动力学仿真平台开发

针对嵌入式车辆动力学仿真平台开发需求,基于吉林大学汽车仿真与控制国家重点实验室的车辆动力学模型,研究了基于d SPACE环境的车辆动力学模型编译、运行控制、参数赋值等关键方法。基于d SPACE嵌入式仿真平台与离线仿真平台验证了车辆动力学模型侧向加速度和横摆角速度的一致性,以及仿真控制策略的可行性和正确性。

A unified 3D space-based navigation model for seamless navigation in indoor and outdoor

Seamless navigation has attracted lots of attention and many methods have been reported in the literature or made available as commercial applications.The process of navigation can be interpreted as a continuous movement of 3D objects from one unoccupied 3D indoor/outdoor space to another.From a technical perspective,a 3D navigation model is one of the critical components that should be available to perform successful navigation.A major approach to build a unified navigation model to support seamless path computation is linking indoor navigation networks to outdoor road/street-based networks.Because of different sources of indoor and outdoor navigation networks,the major approach fails to build up true seamless navigation models.With regards to this,we propose a unified 3D space-based navigation model(U3DSNM).The presented model ensures all types of spaces for navigation(indoor,semi-indoor,semi-outdoor,and outdoor)have the same representation,management methods,and network derivation approach,thereby building up unified navigation networks to support seamless navigation paths planning.The model can be linked to the international standards(data models)that are also based on spaces,such as IndoorGML and the on-going version of CityGML 3.0.Three navigation path planning cases show the feasibility of U3DSNM.

3D space charge code with the FFT method

Precise and fast 3D space-charge calculations have become important for high intensity hadron accelerator design. The PIC method is most frequently used due to its efficiency. This paper introduces a 3D-PIC code that computes the potential of the bunch in the rest frame by means of Poisson＇s equation. FFT is applied as Poisson solvers. The details and the results are presented as well as error analysis.

Performance Evaluation of Three-Dimensional UWB Real-Time Locating Auto-Positioning System for Fire Rescue

Fire rescue challenges and solutions have evolved from straightfor-ward plane rescue to encompass 3D space due to the rise of high-rise city buildings.Hence,this study facilitates a system with quick and simplified on-site launching and generates real-time location data,enabling fire rescuers to arrive at the intended spot faster and correctly for effective and precise rescue.Auto-positioning with step-by-step instructions is proposed when launching the locating system,while no extra measuring instrument like Total Station(TS)is needed.Real-time location tracking is provided via a 3D space real-time locating system(RTLS)constructed using Ultra-wide Bandwidth technology(UWB),which requires electromagnetic waves to pass through concrete walls.A hybrid weighted least squares with a time difference of arrival(WLS/TDOA)positioning method is proposed to address real path-tracking issues in 3D space and to meet RTLS requirements for quick computing in real-world applications.The 3D WLS/TDOA algorithm is theoretically constructed with the Cramer-Rao lower bound(CRLB).The computing complexity is reduced to the lower bound for embedded hardware to directly compute the time differential of the arriving signals using the time-to-digital converter(TDC).The results of the experiments show that the errors are controlled when the positioning algorithm is applied in various complicated situations to fulfill the requirements of engineering applications.The statistical analysis of the data reveals that the proposed UWB RTLS auto-positioning system can track target tags with an accuracy of 0.20 m.

基于dSPACE快速控制原型的驱动电机控制研究

快速控制原型作为半实物仿真技术的一种,其应用使得控制系统的开发、产品型控制器的仿真测试变得更加方便易行,也使得研究人员对控制算法及仿真测试方案的研究更加高效。利用基于d SPACE的快速控制原型建立了实时半实物仿真平台,实现了电动车驱动电机控制试验。试验结果表明,该控制系统能够实现电动车驱动电机的控制,电机能够很好的跟踪控制器输入的期望转速,控制效果良好。

Assessment of Changes in the Cesarean Scar and Uterus Between One and Two Years after Cesarean Section Using 3D T2w SPACE MRI

Objective Io evaluate changes in morphology of the cesarean scar and uterus between one and two years after cesarean section using high-resolution,three dimensional T2-weighted sampling perfection with application optimized contrast using diflerent flip angle evolutions Magnetic Resonance Imaging(3DT2w SPACE MRI).Methods This prospective study was performed to investigate morphological changes in the cesarean scars and uterus from one to two years after cesarean section using high-resolution,3D T2w SPACE MRI.The healthy volunteers having no childbearing history were recruited as the controls.All data were measured by two experienced radiologists.All data with normal distribution between the one-year and two-year groups were compared using a paired-sample t test or independent t test.Results Finally,46 women took a pelvic MR examination one year after cesarean section,and a subset of 15 completed the same examination again after two years of cesarean section.Both the uterine length and the anterior wall thickness after two years of cesarean section(5.75±0.46 and 1.45±0.35 cm)were significantly greater than those measured at one year(5.33±0.59 and 1.25±0.27 cm)(t=-2.363 and-2.175,P=0.033 and 0.048).No significant difference was shown in myometrial thickness two years after cesarean section(1.45±0.35 cm)with respect to the control group(1.58±0.21 cm,P=0.170).Nine women who underwent MRI twice were considered to have scar diverticula one year after cesarean section,and still had diverticula two years after cesarean section.The thickness,height,and width of the uterine scar showed no significant change from one to two years(all P>0.05).Conclusions 3D T2w SPACE MRI provides overall morphologic details and shows dynamic changes in the scar and the uterus between one and two years after cesarean section.Scar morphology after cesarean section reached relatively stable one year after cesarean section,and uterine morphology was closer to normal two years after cesarean section.